1. Field of the Invention
This invention is directed to wellbore drilling operations; systems for drilling auxiliary holes such as conductor holes, ratholes, and mouseholes useful in such operations; and methods of forming such auxiliary holes.
2. Description of Related Art
The prior art discloses a variety of methods and systems for drilling operations; for example, and not by way of limitation, those disclosed in U.S. Pat. Nos. 2,810,550; 3,340,938; 3,719,238; 3,807,109; 3,922,825; 3,942,593; 4,269,395; 4,290,495; 4,368,602; 4,421,179; 4,442,904; 4,489,526; 4,569,168; 4,809,788; 4,837,992; 4,875,530; 5,038,871; 5,199,507; 5,351,767; 5,468,121; 5,544,978; 6,209,851; 6,634,436; 6,523,319 and the references cited in these patents—all these patents incorporated fully herein for all purposes. The formation of auxiliary holes such as conductor holes, ratholes, and mouseholes and the use of such holes is common in such drilling operations. FIG. 1 illustrates a prior art drilling system.
In many drilling operations, prior to drilling a main wellbore, auxiliary holes such as a conductor hole, rathole, or mousehole are drilled near the location of the main wellbore. Typically, an auxiliary hole is drilled by a relatively small portable rig rather than by the drilling system that will be used to drill a main wellbore. Once the auxiliary hole has been drilled, the portable rig is removed. A variety or problems are associated with the use of such rigs; often including difficulties in transporting such rigs to remote locations where the main wellbore is to be drilled. Often, if auxiliary hole drillers are not available or cannot reach the drill site, some drillers use the kelly to drill these holes. Using the kelly to drill these holes can be dangerous to employees and personnel, since the workers have to pull the kelly over by hand or with winches to these holes and the resistance and weight of this equipment can make it difficult to maintain a precise drilling angle. This can lead to inaccurate angles for these holes which is undesirable. Guiding the drilling of an auxiliary hole with a kelly can be extremely difficult. The drill bit can move in any direction and precision can be lost. Also for kelly drilling, a rig mud system must be operational.
U.S. Pat. No. 3,719,238 discloses a compact, mobile, portable rotary drilling rig which enables the use of pipe of a length slightly less than the height of the mast. The drilling rig has a power driven swivel or drilling head connectable to a drill pipe, which swivel may be pulled down by a hydraulic cylinder-plunger arrangement, which cylinder is about one-half the length of the distance which the swivel is to be pulled down, and which cylinder is so constructed that no hoses are connected directly to the movable hydraulic cylinder. The hydraulic cylinder exerts tension on cables to perform the pull down action. Provision is made to mount the present compact, mobile, rotary drilling rig, including the mast, on a vehicle which may be enclosed in van-like insulated structure. In certain aspects such a portable drilling rig has: a base; a prime mover mounted on the base; an upstanding mast mounted on said base; a fluid powered swivel mounted on the mast for movement longitudinally thereof in guided relation; a fluid pump connected in driven relation with the prime mover; a piston rod having two hollow portions, mounted longitudinally of and within the mast and having a fluid blockage therein between the hollow portions; a movable fluid cylinder mounted on the hollow piston rod and being longitudinally movable with respect thereto; packing sealing the ends of the cylinder with respect to the hollow piston rod; a piston mounted on the piston rod within the length of the fluid cylinder; cable sheaves mounted on each end of the fluid cylinder; further cable sheaves mounted near each end of the mast; at least two cables connected to the fluid powered swivel and extending in opposite directions over the sheaves at each end of the mast and over the sheaves at each end of the cylinder, with a portion of the cable being restrained against substantial movement at each end of the mast; pressure control apparatus for directing fluid under pressure into the cylinder through on the portion of the hollow piston rod at one end thereof on one side of the piston and directing fluid under pressure out of the fluid cylinder on the other end of the piston and on the other side of the blockage in the hollow piston rod into the other portion of the hollow piston rod to move the cylinder relative to the piston by fluid pressure so as to move the swivel longitudinally of the mast by means of the cables connected thereto.
U.S. Pat. No. 4,421,179 discloses well drilling apparatus including a powered drilling unit connectable to the upper end of a drill string and adapted to rotate it to drill a well, and a vertically extending guide track structure which guides the drilling unit for movement along the axis of the well, with a portion of the guide track structure being mounted for swinging movement between a drilling position in which the drilling unit is aligned with the axis of the well and a slightly inclined position in which the track structure guides the drilling unit for movement along an inclined axis in alignment with a mousehole, and with the drilling unit also preferably being mounted for movement to a laterally retracted position at a side of the well in which it leaves an area along the axis of the well unobstructed for use of conventional hoisting equipment in making a round trip of the drill string out of and then back into the well. In one aspect such a well drilling apparatus includes: a mast or derrick; a drilling unit including an element adapted to be connected to the end of a drill string for rotation therewith about the axis of the string, and a motor operable to drive the element and the connected string rotatively about the axis; a pair of elongated first guide rails; a pair of shorter second guide rails forming lower extensions of the first rails; a carriage by which the drilling unit is carried and engaging the rails for movement therealong between an upper position of guided engagement with the first rails and a lower position of guided engagement with the second rails; pivotal connection means mounting the first rails near their upper ends for swinging movement of the first rails and the second rails and the carriage and carried drilling unit relative to the mast or derrick between drilling positions in which the carriage and drilling unit are guided by the first and second rails for movement along the axis of the drill string and inclined positions in which the first and second rails extend at an angle to the axis and guide the carriage and drilling unit for movement along an inclined path at an angle to the axis for access to a mousehole; and a connection mounting at least one of the second rails to a corresponding one of the first rails for movement therewith between the drilling and inclined positions, and for swinging movement relative thereto with the carriage and drilling unit to move the drilling unit from an active position of alignment with the axis to a retracted position at a side of the axis.
U.S. Pat. No. 5,038,871 discloses drilling equipment including apparatus for laterally moving a direct drive drilling unit to a position offset from the centerline of a well. The drilling equipment includes a traveling block suspended for generally vertical travel within a derrick during drilling of a well, a direct drive drilling unit suspendable from the traveling block, means for guiding the drilling unit during drilling and apparatus connected to the derrick for moving the drilling unit laterally relative to the axis of the well to an offset position. The drilling unit includes a drill motor and a drive sleeve for threadably connecting the drill motor to a drill string in the well. The guide means includes a first pair of rails connected to the derrick and extending parallel to the axis of the well. The apparatus includes a second pair of rails and means for supporting the drilling unit. The second pair of rails is positionable below and in alignment with the first pair of rails when the support means is in the offset position. In one aspect such equipment includes: means for suspending equipment for generally vertical travel within the derrick; a power swivel suspendable from the suspension means, said power swivel including a drill motor for rotating a drill string in a well, means for guiding the power swivel during travel, the guide means including a first pair of rails connected to the derrick and extending parallel to the axis of the well, and apparatus connected to the derrick for moving the power swivel laterally relative to the axis of the well to an offset position, the apparatus including a second pair of rails and means for supporting the power swivel, the second pair of rails being positioned below and in alignment with the first rails when the support means is in the offset position whereby the suspension means can travel the full length of the first and second pair of rails when the support means is in the offset position.
U.S. Pat. No. 5,544,978 discloses a machine for simultaneously augering and thrusting an anchor into the ground for later attachment of a utility pole or road sign. A vehicle is used to transport the thruster machine with a hydraulic control system such that a rail track is moved into thrusting position and locked in place. A winch, plus a system of hydraulic pistons will raise and lower an auger and thrusting device into the position desired. With an anchor affixed to the bottom of a platform, the auger is then used to drill out the dirt and other material so that the anchor may be more easily inserted into the ground. The thrusting process is facilitated by an indexing feature contained within the platform. A series of hydraulic pistons drive the anchor into the ground until fully stroked, whereupon the platform is re-indexed as needed to completely sink the anchor. A counter-thrust device may also be employed to stabilize the vehicle during the thrusting operation. Upon completion of the thrusting process, the platform is disengaged from the anchor and raised to its starting position. The rail track is then lowered back onto the flatbed truck, and the vehicle can then be driven to the next desired location for sinking an anchor. In one aspect a combined auger and thruster machine for driving anchors into the ground is disclosed that has: a thrust rail track maintainable in a stationary position, the thrust rail track having a top, the thrust rail track having a pair of spaced apart channel members interconnected by a plurality of cross-piece members, each the channel members having a plurality of dog receiving holes; a platform movable upon the thrust rail track, the platform having a dog wall assembly received by the channel members, the dog wall assembly having a dog piston to selectively engage a plurality of dogs that are received by the dog receiving holes, the platform having a platform wall, wherein the platform wall and the dog wall assembly are slidably interconnected by a plurality of pistons, the platform wall adaptable to receive an anchor, the anchor having an axial bore; and an auger carried by the platform and passing through the axial bore when the anchor is received by the platform, said plurality of pistons driving the platform with attached anchor and the auger when the plurality of dogs are received in the dog receiving holes.